oprofile/x86: remove node check in AMD IBS initialization

Standard AMD systems have the same number of nodes as there are
northbridge devices. However, there may kernel configurations
(especially for 32 bit) or system setups exist, where the node number
is different or it can not be detected properly. Thus the check is not
reliable and may fail though IBS setup was fine. For this reason it is
better to remove the check.

Cc: stable <stable@kernel.org>
Signed-off-by: Robert Richter <robert.richter@amd.com>